The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 25, 2000
Filed:
Aug. 20, 1998
Tetsumasa Okamoto, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A partial oxide film on a base region is removed to form an opening, a polycrystalline silicon film is deposited directly thereon, and by dry etching, the polycrystalline silicon film is divided into a region including an impurity of same conductive type as the base, and a region including an impurity of reverse conductive type of the base. By heat treatment, the impurity is diffused from the polycrystalline silicon film into the base region, and an external base diffusion layer and an emitter diffusion layer are formed. In succession, the surface of the polycrystalline silicon film is formed into polyside film to lower the resistance, and by using the polycrystalline silicon film as emitter electrode and base electrode, a fine base and emitter area is realized.